Zero to GP - GP Revision Podcast
The Zero to GP podcast helps you learn and revise the key facts that you need for your GP exams. It is for educational purposes only. The information is not medical advice and should not be used to guide patient management. There may be errors - always check with the appropriate policies, guidelines and colleagues.
Zero to GP - GP Revision Podcast
Herpes Simplex Virus - Essential GP Revision
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Herpes simplex virus for general practice exams.
Video version: https://youtu.be/fQ4kH_dkXlM
Notes, questions and flashcards: https://zerotogp.com/
Books and flashcards: https://zerotofinalsshop.com/
Full AKT Revision Course: https://zerotofinals.com/courses/zerotoakt/
Hi, this is Tom, and in this episode, I'm going to be going through herpes simplex virus. As always, the format of these episodes in the Ser2GP podcast are I'm going to present you with cases and ask you questions. I want you to come up with your answer in the pause. Ideally, say it out loud or write it down so you know whether you truly know that information, and then we'll go through an explanation. So let's jump straight into this episode. The first episode we, or the first case that we have is a 21-year-old man and he presents with a painful with painful blisters in the corner of his lip.
SPEAKER_00My question to you is what is the diagnosis here?
SPEAKER_01This is herpes labialis, labialis meaning in reference to the lip, or just commonly known as a cold sore.
SPEAKER_00My next question is what type of herpes simplex virus causes cold sores? Herpes simplex virus type one or HSV one.
SPEAKER_01What is the cause of recurrent cold sores? Why is it that some people get recurrent episodes of cold sores? It's caused by the virus remaining dormant in the trigeminal ganglion at the side of the face. So the virus lives in this ganglion, it remains dormant, it's not causing any symptoms, and then during times of stress or triggered by you know various uh potential triggers, but particularly stress or being run down or immunocompromised for some reason, that virus can reactivate and cause a recurrent episode of a cold sore. My next question is: what's typical cold sore treatment? How can this patient treat this painful blistering lesion? Treatment is with uh antiviral drugs, specifically acyclovir or val acyclovir. And these this aclovir could be used topically in the form of, say, cream. This is usually over the counter, it's not a prescribed treatment. So they can buy cold sore treatment cream that contains acyclovir and use that. It should be used from the moment they feel any uh prodromal symptoms, so potentially some tingling or numbness around that area before the cold sore appears. Using the cream early is helpful. The other is oral treatment with acyclovir or valacyclovir, which involves tablets five times a day for at least five days until from the moment the symptoms first start until they're completely resolved. Uh oral treatment does require a prescription. My next patient, the next patient we go through, is a 30-year-old woman, and she presents with painful red blisters and ulcers on her genitals. And she's also got systemic symptoms, or she's got some dysuria, so pain when she passes urine, she's got a headache, she feels run down, and she's got a fever. My question to you is what type of HSV typically causes genital herpes infection?
SPEAKER_00This is typically caused by HSV type 2 or HSV2.
SPEAKER_01HSV1 from cold sores can cause genital lesions, which would be spread by oral genital sex. But typically, genital herpes is caused by HSV2. My next question is let's say you've got a patient presenting with this, there's various diet uh various differential diagnoses for genital ulceration or painful lesions. What would be the diagnostic test to confirm uh genital herpes? You can take a viral swab for PCR testing, and this may you need a sample of the fluid from inside one of the blisters or vesicles, and this may involve um popping one of the vesicles to get a sample of that fluid. My next question is why does recurrent genital herpes occur? Why do the episodes keep reoccurring after the first episode? This happens because the virus lies dormant in the sacral ganglia. Unlike uh or with the with herpes labialis or cold sores, the virus lies dormant in the trigeminal ganglia. With genital herpes, it's the sacral ganglia. My next question is how is genital herpes transmitted?
SPEAKER_00What's the transmission?
SPEAKER_01It's transmitted by sexual activity or close skin contact. And this can happen even if the person is asymptomatic and even if they're using condoms. So both of these, if they're asymptomatic, that will be a much reduced risk of transmitting compared with patients who have symptoms. The risk is much higher if they're symptomatic, but there's still some viral shedding even if they're asymptomatic. And you can still contract it if using condoms effectively. However, condoms do reduce the risk quite significantly. And because the virus can lie dormant for many years, somebody may contract it from a partner after being in a monogamous relationship for many years and being asymptomatic all that time. Okay, on to the next question. If somebody has genital herpes and they're pregnant, what is the risk to the fetus? The risk is that the fetus contracts the herpes virus during delivery and they've got a neonatal herpes infection. The risk is particularly higher if the first episode occurs during pregnancy, and particularly if the first episode occurs during the third trimester of pregnancy. So the rules on whether the mother gets antiviral therapy and whether cesarean section is recommended and so on depends on when the infection occurs and whether this is the first infection or reactivation of a recurrent infection. So when it's the first episode, particularly in the third trimester, there won't have been enough time for the mother to make antibodies and for those antibodies to cross the placenta to the fetus and protect the fetus during delivery. If it's a recurrent infection, the mother will have lots of HSV antibodies, and those antibodies will cross to the fetus, and then during delivery, the fetus will have some protection against the herpes virus, and so is much less likely to get neonatal herpes infection. Okay, on to our next case, which is let's say a 40-year-old man, and he presents with a painful red eye. And his eye is red, and when you apply fluorescein, you can see this branching tree-like um lesion across the front of the eye shining uh showing up with the fluorescein.
SPEAKER_00What's your suspected diagnosis here?
SPEAKER_01Suspected diagnosis here is herpes keratitis, where there's a herpes infection of the cornea at the front of the eye. And this gives a dendritic corneal ulcer. Dendritic refers to this appearance of it kind of branching out like a tree. Um, and so when you sh when you add the fluorescene stain, you see this kind of webbed branching kind of appearance to the ulcer at the cornea. Okay, on to the next case, which is a five-year-old girl, and she's got a background of eczema, and she presents with a painful vesicular rash. Her mum may say she's she did have some eczema in that area, now it's become very red, a bit blistery, and very painful. She's also got a fever and lymphatinopathy, so she's somewhat systemically unwell.
SPEAKER_00What's your suspected diagnosis here?
SPEAKER_01Here you're suspecting eczema herpeticum, which is herpes simplex virus, typically HSV1, uh infecting heczamitous skin. So there's a there's a quite a um a widespread herpes infection of the skin. This is quite a serious diagnosis, and they need immediate admission to hospital and usually intravenous antiviral drugs like Ocyclobe. On to the final case, which is a 46-year-old man and he presents with a painful blistering lesion on his fingertip.
SPEAKER_00What's your suspected diagnosis here?
SPEAKER_01This is herpetic whitlow, meaning that the herpes simplex virus has infected the skin, typically around the nail on the tip of the finger. This is quite contagious, so just like any other herpesimplex virus infection, it can be spread, and um they may need treat or they'll need treatment with systemic antiviral drugs. So thanks for listening to this episode. Hopefully, it was helpful for your exam preparation. Um, have a look at the Zero to GP AKT revision book, which contains all the keynotes and facts you need for your GP exams. I've also got an upcoming Zero to GP AKT revision course in London on the 13th of September. Head over to the link in the description to check out more on that, including some amazing testimonials from past courses where people were failing their exams and then they've absolutely sailed through with the help of this course. And there's the zero2gp.com site, which is a full question bank, fact trainer tool, which is anki like and helps you do space repetitions of the key facts for your GP exams, flashcards and notes, all on that site covering the full AKT curriculum. Head over and check that out. There's a link in the description. And I'll see you in the next Zero to GP episode.